use strict;
use warnings;
use File::Basename qw( fileparse );

my $first='';
my $second='';

while (<DATA>) {
    $first = $second;
    (undef, $second) = fileparse( $_ );
    print "$second\n" if eof DATA;  
    next unless $first;
    unless ( $second =~ /\Q$first/) {
        print "$first\n";
    }
}


__DATA__
testing123/
foobar/
helloworld/
helloworld/r1/
helloworld/r1/helloworld-5-0.noarch.rpm
helloworld/r1/testfile23.txt
helloworld/r1/tomcat-7.0.27.rpm
helloworld/r2/
helloworld/r2/helloworld-2-0.noarch.rpm
helloworld/r2/testfile12.txt
helloworld/r2/tomcat-5.0.52.rpm
hellotest/test.txt
hellotest/